Ski boot



FIG. 1 is a left side elevation of our new design for a ski boot;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a front elevation thereof;

FIG. 4 is a right side elevation thereof;

FIG. 5 is a top plan thereof; and,

FIG. 6 is a bottom plan thereof. 

The ornamental design for a "ski boot" substantially, as shown and described. 